Pallet wrap machines are used to wrap stretch film around pallets to retain a product load on the pallet. The amount of stretch film usage is an important cost factor for a company, especially for a company with high volume wrapping requirements. It is therefore important to maintain optimized machine settings at all times in order to minimize film usage and keep film costs down.
However, stretch film usage using such machines can vary over time despite starting with optimal machine settings. Changes in the amount of film used can arise from a number of factors including machine wear and unauthorized adjustments to machine settings. It is therefore valuable to be able to monitor the amount of film being used to be able determine whether optimal usage is being maintained.
There are very few ways to determine the amount of film being used by a stretch wrapping machine. U.S. Pat. No. 8,001,745 issued Aug. 23, 2011, the contents of which are herein incorporated by reference, describes a system for monitoring and controlling usage of stretch film. This system involves the use of a rotary encoder collar securable to a pre-stretch roller of the wrapping machine, proximity sensors for counting revolutions of the rotary encoder and film detection sensors mounted proximate the center and the periphery of the film roller. However, because the rotary encoder collar monitors the rotation of the pre-stretch roller, the encoder does not directly measure the amount of film passing over the pre-stretch roller. There is only an implied relationship between the rotation of the pre-stretch roller and the length of film that passes over the roller, and this relationship may not accurately reflect the amount of film actually used due, at least in part, to slippage between the rollers of the machine and the film.
There remains a need to better monitor and control the use of stretch film in a pallet wrap machine.